A crossed-field antenna (“CFA”) is a type of antenna designed for long and medium wave broadcasting. Conventional CFAs were first developed by Hately & Kabbary (see U.S. Pat. No. 5,155,495, issued 13 Oct. 1992; U.S. Pat. No. 6,025,813, issued 15 Feb. 2000; and U.S. Pat. No. 7,113,138, issued 26 Sep. 2006). These authors describe an antenna with two parts, one of which produces a high frequency electric field, and the other of which produces a high frequency magnetic field. The electric and magnetic field lines are arranged to cross, and thereby synthesize and propagate radio waves. CFAs based on the Hately and Kabbary design typically consist of two driven elements and a ground plane in various configurations, tuned by means of one antenna tuning unit (“ATU”) or feed circuit.
Such CFAs were touted as a highly efficient antenna design that uses far less height than conventional antennas. Although there was initial excitement about such antennas in the 1980s and early 1990s, the efficiency of prior art designs, based on real-world testing, did not live up to the initial expectations.
Because these initial CFA designs were not as efficient as initially expected, there is a need for a design that retains the size advantages of a conventional CFA, but is capable of high efficiency for its size.